{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "1.7.3"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "76ee6a59bf5773c0af00b99076c5e199031f97f1"
            }
          ],
          "repo": "https://github.com/authlib/joserfc",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-r74j-q665-7rpj"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-290",
      "CWE-345"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/75xxx/CVE-2026-75509.json"
  },
  "details": "joserfc is a Python library that provides an implementation of several JSON Object Signing and Encryption (JOSE) standards. Prior to version 1.7.3, JWTClaimsRegistry applies membership matching to list-valued iss and sub claims, allowing an array-valued iss that contains the expected issuer to pass an intended equality check and enabling issuer-validation bypass. This issue is fixed in version 1.7.3.",
  "id": "CVE-2026-75509",
  "modified": "2026-08-27T11:30:44.851666900Z",
  "published": "2026-08-24T20:08:07.088Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/75xxx/CVE-2026-75509.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/authlib/joserfc/security/advisories/GHSA-r74j-q665-7rpj"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-75509"
    },
    {
      "type": "FIX",
      "url": "https://github.com/authlib/joserfc/commit/76ee6a59bf5773c0af00b99076c5e199031f97f1"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "joserfc claim-validation bypass via array-typed single-string claims (iss/sub/jti)"
}